Okay, so a wormhole is a small hole-like thingy in the time-space continuum. Like, really tiny. Like, inside atoms tiny. But the weird thing about these tiny hole-thingies is that they’re not just holes in space. They’re also holes in time. Basically, if you threw a ball through a hole in a wall, or a hole in a tree, or a hole in most anything, it would come out the other side, right? Well, throw a ball through a hole in the fabric of reality, and it would come out the other side too, only instead of being a different location in space, it would be a different point in time. It would act as a tunnel, linking two specific points in time for a bit, before collapsing (like a tunnel in the ground collapsing shut). Pretty simple, since our generations have been steeped so heavily in sci-fi.

So what if you made it bigger?

If you found a way, using a colossal amount of power and some deep magic, to resize a wormhole, say, the size of a small car, then you could drive said car through time, into the future, or, more interestingly, into the past.

Ah, but we have a problem.

See, you can’t go back in time. It breaks the universe. Badly. Because of the simplest, most fundamental law of all reality: causality. Put simply, cause comes before effect, and never the other way around. There’s a famous explanation of this called the Grandfather Paradox, but I’m going to use Stephen Hawking’s simpler version, the Mad Scientist Paradox. It goes like this:

A mad scientist is desperate to see if he can violate causality. So desperate (and mad) that he’ll give his own life to test the laws of nature. So he constructs a wormhole that leads twenty seconds into the past. While standing in front of the wormhole, he puts together a pistol and loads it. Now he walks around to the other side of the wormhole, and can see himself opening the suitcase that contained the gun, and starting to put it together.

He shoots himself.

Or rather, the version of him 20 seconds ago, who is loading the gun. Other him drops dead. Now, here’s the problem: the gun lies unloaded on the floor, and there is no one to shoot it. So who will kill the man? No one, so he’s still alive. Which means he’s free to kill himself. Which means he lives. Until he dies. But he lives.

Problem.

Now, in physics, if there’s a law that can’t be broken, there’s a mechanism in place to keep that law from being broken. For instance, you can’t go faster than the speed of light. When you get close, time slows down for you. Seriously. So no matter how hard you try, you can’t reach the speed of light, because time slows as you try to speed up.

Stephen Hawking suggests that a similar concept exists to protect causality. Feedback. If you put a speaker in front of a microphone, the sound will feed through the mic, get amplified, and come out of the speakers, to repeat this loop continuously, getting louder each time. Eventually, feedback left unchecked will destroy the sound system. Hawking suggests a similar event would occur with a wormhole, but involving radiation. There is always a small amount of background radiation, no matter where you are in the universe. You radiate it yourself. Light, heat, microwaves, radio waves, cosmic rays, all flying through the air around you all the time. Now let’s revisit that scientist’s wormhole, shall we?

The wormhole opens. Light, sound, and all manner of energy pour in from both sides. Energy from the future pours into the past. And is still here in the future, where it gets thrown through the wormhole. Now all that energy is in the past, which becomes the future. Now all that energy pours through the wormhole into the past. The energy compounds until the wormhole can’t sustain itself and collapses. Now, since most radiation moves at about the speed of light, this would all happen in a blink. No more wormhole. 😦

But being the dreamer I am, I tried to think of a way to visit the past anyways.

My thinking went like this: in order to go back in time without breaking the wibbly-wobbly universe, you would have to be incapable of interacting with it in any way. You could certainly watch events from the past, but you couldn’t change them. So then I got the solution.

What if the wormhole made you ethereal? You attach a tether to a sturdy object, then jump through. On the other side, you’re a ghost. You can see yourself, but no one in that time can see you. You’re invisible, intangible… Gravity and other such forces don’t even effect you. Momentum could still work, as you would carry that energy with you, and it could only effect you. Friction would work too, but only with yourself and your tether. You can’t touch anything else. This would allow you to freely witness historical events, while rendering you incapable of altering timelines. The feedback issue wouldn’t occur, because all of the energy from your world would become ethereal with you, rendering it null.

This would also answer the age old question: if time travel is possible, where are all the time travelers? They’re watching us, silently. Probably not for day to day stuff, because I’d imagine wormholes would be expensive. But at Tiananmen Square, at Occupy Wall Street, at the speeches of MLK, and Hitler, and Jesus. At the stabbing of Caesar, and the shootings of Lincoln and Kennedy. Completely unseen. Stephen Hawking once threw a party for time travelers, and no one showed up. If I’m correct, there could have been hundreds of people there, invisibly watching as Hawking sipped champagne alone.

So, there you go. Thoughts?

(Disclaimer: This is merely a thought experiment, a hypothesis at best. There is no evidence that I am aware of that supports or disputes these claims. This isn’t meant to be a “this is” but a “what if”. And Mr. Hawking, if you somehow are reading this, sorry for disputing you so much. You’re awesome, and if you have another welcome future people party, invite me and I’ll wait with you.)